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    <div class="refentry" id="glClipControl">
      <div class="titlepage"/>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>glClipControl — control clip coordinate to window coordinate behavior</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>C Specification</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glClipControl</strong>(</code>
              </td>
              <td>GLenum <var class="pdparam">origin</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLenum <var class="pdparam">depth</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>origin</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                         Specifies the clip control origin. Must be one of
                         <code class="constant">GL_LOWER_LEFT</code> or
                         <code class="constant">GL_UPPER_LEFT</code>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>depth</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                        Specifies the clip control depth mode. Must be one
                        of <code class="constant">GL_NEGATIVE_ONE_TO_ONE</code> or
                        <code class="constant">GL_ZERO_TO_ONE</code>.
                    </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            <code class="function">glClipControl</code> controls the clipping volume
            behavior and the clip coordinate to window coordinate
            transformation behavior.
        </p>
        <p>
            The view volume is defined by
                $$z_{min} \leq z_c \leq w_c$$
            where $z_{min} = -w_c$ when <em class="parameter"><code>depth</code></em> is
            <code class="constant">GL_NEGATIVE_ONE_TO_ONE</code>, and $z_{min} = 0$
            when <em class="parameter"><code>depth</code></em> is
            <code class="constant">GL_ZERO_TO_ONE</code>.
        </p>
        <p>
            The normalized device coordinate $y_d$ is given by
                $$y_d = { { f \times y_c } \over w_c }$$
            where $f = 1$ when <em class="parameter"><code>origin</code></em> is
            <code class="constant">GL_LOWER_LEFT</code>, and $f = -1$ when
            <em class="parameter"><code>origin</code></em> is
            <code class="constant">GL_UPPER_LEFT</code>.
        </p>
        <p>
            The window coordinate $z_w$ is given by
                $$z_w = s \times z_d + b$$
            where $s = { { f - n } \over 2 }$ and $b = { {n + f} \over 2 }$ when
            <em class="parameter"><code>depth</code></em> is
            <code class="constant">GL_NEGATIVE_ONE_TO_ONE</code>, and $s = f - n$ and
            $b = n$ when <em class="parameter"><code>depth</code></em> is
            <code class="constant">GL_ZERO_TO_ONE</code>. $n$ and $f$ are the near
            and far depth range values set with
            <a class="citerefentry" href="glDepthRange.xhtml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>.
        </p>
        <p>
            Finally, the polygon area computation defined by
            <a class="citerefentry" href="gl_FrontFacing.xhtml"><span class="citerefentry"><span class="refentrytitle">gl_FrontFacing</span></span></a>
            to determine if a polygon is front- or back-facing has its sign
            negated when <em class="parameter"><code>origin</code></em> is
            <code class="constant">GL_UPPER_LEFT</code>.
        </p>
      </div>
      <div class="refsect1" id="notes">
        <h2>Notes</h2>
        <p>
            The default GL clip volume definition is for a
            <em class="parameter"><code>origin</code></em> of
            <code class="constant">GL_LOWER_LEFT</code> and a
            <em class="parameter"><code>depth</code></em> of
            <code class="constant">GL_NEGATIVE_ONE_TO_ONE</code>.
        </p>
        <p>
            An <em class="parameter"><code>origin</code></em> of
            <code class="constant">GL_UPPER_LEFT</code> and a
            <em class="parameter"><code>depth</code></em> of
            <code class="constant">GL_ZERO_TO_ONE</code> corresponds to Direct3D's
            clip volume definition.
        </p>
        <p>
            An <em class="parameter"><code>origin</code></em> of
            <code class="constant">GL_UPPER_LEFT</code> and a
            <em class="parameter"><code>depth</code></em> of
            <code class="constant">GL_NEGATIVE_ONE_TO_ONE</code> corresponds to the
            upper-left origin of the window coordinate system of Microsoft
            Windows and the X Window System.
        </p>
        <p>
            There is extensive discussion of the uses and further
            consequences of the different clip volume settings in the
            <code class="code">GL_ARB_clip_control</code> extension specification in the
            OpenGL Registry at URL <a class="link" href="http://www.opengl.org/registry/" target="_top">http://www.opengl.org/registry/</a>.
        </p>
      </div>
      <div class="refsect1" id="errors">
        <h2>Errors</h2>
        <p>
            An <code class="constant">GL_INVALID_ENUM</code> error is generated if
            <em class="parameter"><code>origin</code></em> is not
            <code class="constant">GL_LOWER_LEFT</code> or
            <code class="constant">GL_UPPER_LEFT</code>.
        </p>
        <p>
            An <code class="constant">GL_INVALID_ENUM</code> error is generated if
            <em class="parameter"><code>depth</code></em> is not
            <code class="constant">GL_NEGATIVE_ONE_TO_ONE</code> or
            <code class="constant">GL_ZERO_TO_ONE</code>.
        </p>
      </div>
      <div class="refsect1" id="versions">
        <h2>Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">
                
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
                <span class="bold"><strong>OpenGL Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function / Feature Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.4</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.5</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">
                  <code class="function">glClipControl</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="gl_ClipDistance.xhtml"><span class="citerefentry"><span class="refentrytitle">gl_ClipDistance</span></span></a>,
            <a class="citerefentry" href="gl_CullDistance.xhtml"><span class="citerefentry"><span class="refentrytitle">gl_CullDistance</span></span></a>,
            <a class="citerefentry" href="gl_FrontFacing.xhtml"><span class="citerefentry"><span class="refentrytitle">gl_FrontFacing</span></span></a>,
            <a class="citerefentry" href="glDepthRange.xhtml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>.
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright <span class="trademark"/>© 2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="link" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p>
      </div>
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